The instant invention relates to the field of semiconductors and especially to processes for diffusing metals such as gold into silicon.
In various types of semiconductor components, and more particularly in power components, one tries to reduce the lifetime of the minority carriers in a specific semiconductor layer. For this purpose, one creates in those layers carrier recombination centres. Such recombination centres are liable to correspond to areas wherein gold or platinum diffusion is carried out, or to areas wherein dislocations have been created, for example by implanting electrons, protons, ions, etc.
With ion or proton implantations, it is theoretically possible to obtain higher dislocation densities at selected depths in a semiconductive layer or wafer by selecting the implantation mode. However, such processes do not make it possible to obtain very short lifetimes. Thus, for obtaining very short lifetimes, it is conventionally necessary to use gold diffusion processes, but it is not possible with the processes of the prior art to modulate in the depth direction the gold concentration in the semiconductive layer or wafer wherein the diffusion is carried out.